Table 1.

Experimental methods used to create different microbial diversity levels

Method	References	Principles	Advantage	Disadvantage
Construction	Deacon (1985), Robinson et al. (1993), Setälä and McLean (2004), Wohl et al. (2004), Bell et al. (2005) and Tiunov and Scheu (2005)	Combinations of different microorganisms previously isolated in culture media	Taxa selection	Culture-dependency unrealistic diversity levels
Destruction	Degens (1998), Griffiths et al. (2000), and Griffiths et al. (2004)	Different duration of fumigation events	Realistic diversity levels	Hidden effect (Huston 1997): increase in soil nutrients
Erosion	Griffiths et al. (2001), Griffiths et al. (2004), Wertz et al. (2006, 2007); Baumann et al. (2013), Juarez et al. (2013) and Philippot et al. (2013)	Successive dilutions of a soil suspension	Realistic diversity levels	Hidden effect (Huston, 1997): non-random taxa selection = elimination of rare taxa